Radars for automobile collision avoidance applications present a relatively novel use of the well-known radar technology, especially in the area of Intelligent Vehicle Highway System (IVHS). One possible application is for creating intelligent cruise control, where in the event of a someone suddenly pulling in front of a driver's vehicle on cruise control, the cruise control can sense the intrusion and drop back without interrupting its pre-set cruising speed. For collision avoidance applications, the radar system can give a driver warning, if the driver is driving too fast for the surrounding conditions. The system may even activate the brakes to automatically adapt the vehicle speed to the conditions. However, to be more intelligent, more signal analysis is needed such that the driver does not receive a warning every time a totally innocuous object is encountered.
Radars suitable for automobile applications generally require two types of millimeter-wave (MMW) radar architectures for generating either an FM/CW (frequency-modulated continuous wave) or a pulse waveform, but rarely both. Conventional approaches to implement these two radar architectures require individual radar sub-systems with no commonality in design to be independently implemented. As such, developmental costs associated with having two radar systems are not shared through common hardware modules. Therefore, it would be desirable to implement a radar architecture which provides sub-system modularity and flexibility to be either an FM/CW or a pulse radar. Further, the optimized common hardware can be shared among systems designed for various automobile OEM's.
An FM/CW radar has been known to have the advantage of achieving high sensitivity with low transmitter power, as well as good range resolution as a function of the modulation. A pulse radar generally has the advantage of achieving unambiguous range measurement, whereas the FM/CW radar does not. For example, a pulse radar can measure the range of a moving automobile being tracked without much ambiguity, whereas an FM/CW radar's tracking can easily get confused, especially by any additional moving objects on the road. With simple processing of the pulse waveform, the slight ambiguity can be removed.